OXYLOS (or Oxylus) was a rustic saimon (Spirit) of the forests of Mounts Oita (Oeta) and Othrys in Malis. He was a son of Oreios ("the Mountain") and the husband of Hamadryas ("She-with-Tree"). They had eight daughters, the Hamadryad nymphs, who each presided over a specific type of tree, and a son Andraimon, an early king of the Dryopes.

Oxylos' name is perhaps derived from the term axylos hylê, virgin mountain forest. Alternatively it could be connected with oxya, the beech-tree (Fagus silvata). If this is the case his wife Hamadryas is probably the drys, or oak, rather than drys, a tree in general.

Oxylos appears to be related to Hekateros and Seilenos, two rustic demi-gods which were also named as the fathers of the Dryades and Satyroi. He might also have been one of the more generic Seilenoi.

ENCYCLOPEDIA

O′XYLUS (Oxulos).A son of Orius, who became the father of the Hamadryades, by his sister Hamadryas. (Athen. iii. p. 78.)

Source: Dictionary of Greek and Roman Biography and Mythology.

Athenaeus, Deipnosophistae 1. 78b (trans. Gullick) (Greek rhetorician C2nd to C3rd A.D.) :
"The Epic poet Pherenikos (Pherenicus), a Herakleto by birth, declares that the fig (Sykon) was named from Syke (Fig-Tree), the daughter of Oxylos (Beech-Tree); for Oxylos, son of Oreios (Mountain), married his sister Hamadryas (Plum Tree) and begot among others, Karya (Walnut-Tree), Balanos (Oak-Nut Tree), Kraneia (Cornel-Tree), Morea (Mulberry-Bush), Aigeiros (Poplar-Tree), Ptelea (Elm-Tree), Ampelos (Grape-Vine), and Syke (Fig-Tree); and these are called Nymphai Hamadryades, and from them many trees derive their names."

Antoninus Liberalis, Metamorphoses 32 (trans. Celoria) (Greek mythographer C2nd A.D.) :
"Dryops (Oak Face) was the son of the River Sperkheios (Spercheus) and of Polydore (Many Gifts), one of the daughters of Danaos (Danaus). He was king in Oita (Oeta) and he had an only daughter, Dryope (Oak Face). She herself herded the flocks of her father. Now, the Nymphai Hamadryades [probably daughters of Oxylos] were very much attached to her and made her their companion, teaching her to sing to the gods and to dance.
Apollon, seeing her dancing, felt an urge to couple with her. He first changed himself into a tortoise. Dryope, with the other Nymphai, was amused by it and they made a toy of the tortoise. She placed it in her bosom. He changed from a tortoise to a serpent.
The frightened Nymphai abandoned Dryope. Apollon coupled with her and she ran full of fear to her father’s house, saying nother to her parents. When Andraimon (Andraemon), son of Oxylos, later married her, she gave birth to Amphissos, the son of Apollon . . .
He became the king of the places thereabouts.
In Dryopis he established a sanctuary of Apollon. One day, as Dryope was approaching the temple, the Nymphai Hamadryades gathered her up affectionately and hid her in the woods. In her place they caused a poplar to appear out of the ground."